Our model is designed to adjust for this; the figures you see in our forecasts reflect the projected results among likely voters.

But what about everyone else – what we might think of as unlikely voters? Another poll this week, conducted by Suffolk University and USA Today, tried to get at that question. It surveyed 800 adults who either were not registered to vote, or who were registered but said they were not likely to turn out.

Among these adults, 43 percent said they preferred Mr. Obama, while 17 percent backed Mr. Romney. Since quite a few Americans fit into this category – about 4 in 10 adults will not vote in November – it is easy to see how Mr. Obama could have a double-digit lead when they are added back into the total, like in the Kaiser Family Foundation poll. But those adults will not help Mr. Obama any if they do not show up on Nov. 6.